Marijuana use negatively impacts the life course of many of the adolescents who use it; it has been associated with increased risk for multiple psychosocial, mental health, and physical health problems. Racial minorities may be more likely to experience adverse outcomes subsequent to marijuana use, including problems such as: substance use disorders, employment problems, and involvement with the criminal justice system. Neighborhood-level factors represent important but understudied potential determinants of marijuana use and subsequent adverse outcomes, highlighting a critical gap in knowledge that limits our ability to identify effective primary prevention strategies targeted at the neighborhood level. The neighborhood context is uniquely relevant for low-income urban youth, as they are persistently exposed to drug activity, physical disorder, and violence in their neighborhoods, all of which may influence marijuana use and adverse outcomes related to use. With this background, this K01 seeks to: (1) fully characterize patterns of marijuana use among adolescents, cross-sectionally and over time; (2) examine the association between perceptions of neighborhood problems and patterns of marijuana use, cross-sectionally and over time, (3) examine the prevalence of adverse psychosocial outcomes in early adulthood by patterns of marijuana use in adolescence, (4) characterize the spatial association between chronic and severe neighborhood violence, such as homicides and shootings, and patterns of marijuana use in adolescence, and (5) investigate the association between objectively-measured neighborhood-level factors and patterns of marijuana use in adolescence. I will use latent variable analyses to characterize patterns of marijuana use, and the Neighborhood Inventory for Environmental Typologies (NIFETY) tool to assess neighborhood-level factors (i.e., physical disorder, drug activity). Data will come from Dr. Nicholas Lalongo's Baltimore Prevention Program dataset, a longitudinal study of youth in Baltimore, MD, a low-income, urban setting. Supplemental data include violent crime records of Baltimore Police Department, and objective data on neighborhood-level drug activity and physical disorder collected as part of Dr. C. Debra M. Furr-Holden's NIFETY project. The findings will identify modifiable neighborhood-level factors associated with substance use, and will be strategically disseminated so as to inform primary prevention efforts. This research project will be embedded in a comprehensive training program designed to further my strengths and to develop new research skills, under the direction of a team of experts. Research and training activities will assist me in achieving my career goal as a leading, independent investigator in social epidemiology and prevention science, focused on investigating the neighborhood-level determinants, use patterns, and consequences of adolescent marijuana use among low- income, urban youth. This goal reflects my core belief that neighborhood factors - including community violence, drug activity, and physical disorder - negatively impact urban youth and make them more vulnerable to initiate marijuana use, and to experience the adverse effects of use. This K01 will afford me the time to acquire new statistical skills, further develop content expertise in substance use, conduct research, write manuscripts, participate in professional meetings, prepare grant applications based on initial findings, and participate in targeted academic and professional development activities. My training goals for this career development period are to: (1) expand my knowledge of adolescent substance use, particularly among low- income, urban youth; and (2) develop skills in the following four methodological areas: analysis of correlated data, latent variable analysis, spatial analysis and mapping, and environmental assessment. I will achieve these goals through formal didactic experiences (i.e., workshops, directed readings, and coursework), and by conducting research under the mentorship of a team of experts in relevant fields of study. In the final stages of this K01 award period, I plan to submit an R01 to NIDA to further investigate the association between neighborhood-level factors and adolescent marijuana use, ideally within the setting of Boston, MA. In addition to building toward an R01 application, I will also use the protected time afforded by this career development award to develop additional grant ideas in this field of research.